Robust synchronization of different coupled oscillators: Application to antenna arrays

This paper deals with the synchronization of a chain of nonlinear and uncertain models of nonidentical oscillators. Using Lyapunov's theory of stability, a dynamical controller guaranteeing the synchronization of the oscillators is determined. The problem of synchronization is transformed into a problem of asymptotic stabilization for a nonlinear system and then is formulated as a system of linear matrix inequalities where the parameter variations of the two oscillators and their differences are modeled by polytopic matrices. The theoretical result is successfully applied to an array of transistor-based oscillators used in “smart antenna” systems.     

Interference suppression of linear antenna arrays by phase-only control using a clonal selection algorithm

In this paper, an efficient technique based on clonal selection algorithm (CLONALG) for linear antenna array pattern synthesis with null steering by controlling only the element excitation phases is presented. The CLONALG is an evolutionary computation method inspired by the clonal selection principle of human immune system. To show the versatility and flexibility of the proposed CLONALG, some examples of Chebyshev array pattern with the imposed single, multiple and broad nulls are given. The sensitivity of the nulling patterns due to small variations of the element phases is also investigated.     

New types of topological superconductors under local magnetic symmetries

We classify gapped topological superconducting (TSC) phases of one-dimensional quantum wires with local magnetic symmetries, in which the time-reversal symmetry is broken, but its combinations with certain crystalline symmetries, such as , , and , are preserved. Our results demonstrate that an equivalent BDI class TSC can be realized in the or superconducting wire, which is characterized by a chiral Z^c invariant. More interestingly, we also find two types of totally new TSC phases in the and superinducting wires, which are beyond the known AZ class, and are characterized by a helical Z^h invariant and Z^h⊕Z^c invariants, respectively. In the Z^h TSC phase, Z pairs of Majorana zero modes (MZMs) are protected at each end. In the case, the MZMs can be either chiral or helical, and even helical-chiral coexisting. The minimal models preserving or symmetry are presented to illustrate their novel TSC properties and MZMs.     

Optimization of microfluidic microsphere-trap arrays

Microarray devices are powerful for detecting and analyzing biological targets. However, the potential of these devices may not be fully realized due to the lack of optimization of their design and implementation. In this work, we consider a microsphere-trap array device by employing microfluidic techniques and a hydrodynamic trapping mechanism. We design a novel geometric structure of the trap array in the device, and develop a comprehensive and robust framework to optimize the values of the geometric parameters to maximize the microsphere arrays'' packing density. We also simultaneously optimize multiple criteria, such as efficiently immobilizing a single microsphere in each trap, effectively eliminating fluidic errors such as channel clogging and multiple microspheres in a single trap, minimizing errors in subsequent imaging experiments, and easily recovering targets. We use finite element simulations to validate the trapping mechanism of the device, and to study the effects of the optimization geometric parameters. We further perform microsphere-trapping experiments using the optimized device and a device with randomly selected geometric parameters, which we denote as the un-optimized device. These experiments demonstrate easy control of the transportation and manipulation of the microspheres in the optimized device. They also show that the optimized device greatly outperforms the un-optimized device by increasing the packing density by a factor of two, improving the microsphere trapping efficiency from 58% to 99%, and reducing fluidic errors from 48% to a negligible level (less than 1%). The optimization framework lays the foundation for the future goal of developing a modular, reliable, efficient, and inexpensive lab-on-a-chip system.     

Improving relational similarity measurement using symmetries in proportional word analogies

Measuring the similarity between the semantic relations that exist between words is an important step in numerous tasks in natural language processing such as answering word analogy questions, classifying compound nouns, and word sense disambiguation. Given two word pairs (A, B) and (C, D), we propose a method to measure the relational similarity between the semantic relations that exist between the two words in each word pair. Typically, a high degree of relational similarity can be observed between proportional analogies (i.e. analogies that exist among the four words, A is to B such as C is to D). We describe eight different types of relational symmetries that are frequently observed in proportional analogies and use those symmetries to robustly and accurately estimate the relational similarity between two given word pairs. We use automatically extracted lexical-syntactic patterns to represent the semantic relations that exist between two words and then match those patterns in Web search engine snippets to find candidate words that form proportional analogies with the original word pair. We define eight types of relational symmetries for proportional analogies and use those as features in a supervised learning approach. We evaluate the proposed method using the Scholastic Aptitude Test (SAT) word analogy benchmark dataset. Our experimental results show that the proposed method can accurately measure relational similarity between word pairs by exploiting the symmetries that exist in proportional analogies. The proposed method achieves an SAT score of 49.2% on the benchmark dataset, which is comparable to the best results reported on this dataset.     

三角阵列的中偏差

利用截尾方法在一定尾概率条件下得到了三角阵列{Xn,j;1≤j≤kn,n≥1}的中偏差,其中{kn;n≥1}是一列严格单调递增的正整数且对任意的正整数n,{Xn,j;1≤j≤kn}是独立同分布的.     

梯形翅片状薄壁半圆锥天线的加工工艺

针对一种特殊结构外形的天线,利用材料的塑性变形,采用普通工艺和特种工艺相结合的方法进行加工。文章介绍了该天线加工成形的详细过程。     

短波发射天线系统维护方法探讨

天线是电台发射的重要设备。一般来讲新架设的天线,馈线系统,通过检验投入使用之后,就需要加强管理和维护。因为在这个时期,天线系统最容易暴露出安装中存在的"隐患"。尤其是短波发射天线,它种类繁多,造价高,占地面积大,制作与安装都比较复杂。因此,对维护工作有了更高的要求。     

一种电磁偶极子超宽带微带天线设计

提出了一种超宽带微带天线结构,由电偶极子和磁偶极子贴片单元组成,水平贴片部分为电偶板子,垂直方向上的短路贴片天线相当于磁偶板子,采用T型馈线激励.仿真结果表明,通过在底板周围添加金属围栏,实现了2.3GHz~7.56GHz的阻抗匹配带宽,相对带宽达到107％.工作频段内实现了稳定的增益和方向图,具有良好的前后比和交叉极化指标.     

一种短波全向宽带小型化天线

为了在短波频段内实现天线的小型化和宽带工作特性,采用遗传算法和矩量法相结合的优化算法,对鞭状天线的集总加载元件值、位置以及匹配网络参数进行优化筛选。同时在满足性能要求的前提下,选择较少的加载点数目和加载电路中元件个数,以便于天线的加工制作和实验调整。最后,制作了一付样品天线。经测试,仿真结果与实测结果吻合良好,表明该天线在较宽的频带内达到了满意的阻抗特性和方向图特性。     

Emerging open-channel droplet arrays for biosensing

Open-channel droplet arrays have attracted much attention in the fields of biochemical analysis,biofluid monitoring,biomarker recognition and cell interactions,as they have advantages with regard to miniaturization,parallelization,high-throughput,simplicity and accessibility.Such droplet arrays not only improve the sensitivity and accuracy of a biosensor,but also do not require sophisticated equipment or tedious processes,showing great potential in next-generation miniaturized sensing platforms....